1. Field of the Invention
This invention pertains to lubrication oil additives and particularly relates to multi-functional additives which are reaction products of at least one basic nitrogen-containing compound, at least one inorganic phosphorus-containing compound, and at least one mono- or di-sulfide-containing alkanol.
2. Discussion of Related Art
Additives for lubrication oil possessing improved friction, extreme pressure, and anti-wear performance are continually sought, particularly in view of more stringent requirements for these additives.
Various approaches have been suggested for obtaining these benefits. For example, U.S. Pat. No. 4,702,850 discloses a process to improve friction modification properties of a power transmission fluid. The process uses a friction modifying agent comprising the reaction product of a thio-bis-alkanol and an aliphatic hydrocarbon-substituted succinic acid or anhydride.
U.S. Pat. No. 4,857,214 describes compositions useful as anti-wear and extreme pressure additives in lubrication oils and methods for preparing these compositions which comprise oil-soluble reaction products of inorganic phosphorus-containing acids or arthydrides with a boron compound and ashless dispersants, such as alkenyl succinimides.
European Appln. No. 92307448.8 (corresponding to Publication No. 0531000) teaches oil additive concentrates which enhance performance, particularly extreme pressure and anti-wear performance. European Appln. No. 92307448.8 discloses combining at least one oil-soluble additive composition formed by first heating at least one ashless dispersant containing basic nitrogen and/or at least one hydroxyl group with at least one inorganic phosphorus-containing compound (at least one boron-containing compound may be included) and then combining the resulting product with at least one oil-soluble metal-free sulfur-containing anti-wear and/or extreme pressure agent. European Appln. No. 92307448.8 teaches concentrates which require highly reactive (corrosive) sulfur-containing anti-wear or extreme pressure agents to "sulfurize" the phosphorylated dispersant.
Another approach for improving both friction modification and anti-wear properties is found in the additives of the present invention.